Farmers and growers all over the world are faced with pests, insects and diseases that may harm the plants, their leaves and their fruits. In order to combat these threats farmers can use pesticides and insecticides by applying them onto the foliage.
“Organic” growers are usually reluctant to use pesticides and insecticides, as they are considered to be harmful to humans and animals. The “organic” growers would usually prefer to use non-toxic pesticides and insecticides whenever possible.
It is well known, and has been in practice for many years now, that botanical oils such as almond oil, soy bean oil, cotton seed oil, castor oil and canola oil, for example, can be used as pesticides and insecticides and to control certain diseases common in agriculture. Many botanical seeds and beans contain minute amounts of highly toxic agents. For example, the almond seeds contain cyanide and the castor seeds contain ricin both of which are highly toxic in large quantities, yet are not harmful to humans in small doses and are used as a natural defense mechanism by the plants against pests and insects.
In order to effectively deliver the botanical oils to the plants as pesticides and insecticides, they must be emulsified with water. This emulsification creates tiny droplets of oil in the water allowing the farmers to spray the emulsion onto the plants using standard spraying mechanisms.
Several methods of producing such emulsions are known and used in agriculture these days:
High pressure emulsifiers operate with high pressure oil injected into water stream through a porous filter in order to shear the oil into small droplets. The oil pressure in these systems may go up to 2000 BAR (over 29000 PSI) or even beyond that. Droplet size coming out of such emulsifiers is typically about 1 micron average diameter. An example for such a high pressure emulsifier is the EmulsiFlex-055, made by Avestin Inc.
A second technique involves high shear emulsifiers which use a two part mechanism—a stator and rotor where the rotor rotates within the stator. The stator and rotor are placed in a heated container containing a mixture of water and oil. When the rotor rotates within the stator while in the container, the oil is thrown from the inner part of the rotor to its outer side through the rotor by centrifugal forces and due to the shape of the rotor and stator; the oil is sheared into small drops. As the process continues on, the oil drops are sheared repeatedly, creating smaller and smaller droplets. The main disadvantage of the high shear emulsifiers is that there is very little consistency in the size of the oil droplets within the emulsion unless the process is continued for a very long time. An example of high shear emulsifier is the ZGF210 made by Shanghai Chengxing M&E Co., Ltd.